Welding material and welding method of high-strength weathering steel for railroad bridge

Abstract

The invention provides a solid-core welding wire and a welding method for high-strength weathering steel for a 500MPa-grade railway bridge by adopting the solid-core welding wire. The solid welding wire comprises the following chemical components in percentage by mass: 0.02%-0.08% of C, 1.10%-1.60% of Mn, 0.18%-0.60% of Si, less than or equal to 0.01% of P, less than or equal to 0.005% of S, 0.40%-0.60% of Cr, 0.30%-0.60% of Ni, 0.30%-0.45% of Cu, 0.05%-0.20% of Mo, less than or equal to 0.05% of V and the balance of Fe and inevitable impurities. According to the welding method, welding parameters are set as follows: the welding voltage is 26-30 V, the welding current is 260-300 A, the welding speed is 30-40 cm / min, the welding heat input is 12-15 kJ / cm, and the protective gas flow is 15-20 L / min; and after each welding seam is completed, the next welding seam is welded when the temperature of the welding seam is less than or equal to 150 DEG C.

Description

Technical Field

[0001] The invention belongs to the field of alloy materials and metal welding, and in particular relates to a new welding material suitable for arc welding of high-strength weathering steel, and a welding method of high-strength weathering steel using the welding material. Background Art

[0002] In order to meet the needs of railway construction, railway steel bridges are rapidly developing in the direction of heavy load, large span and full welding. Therefore, the strength grade of steel for railway bridges is constantly improving, and the demand for special properties such as atmospheric corrosion resistance is becoming stronger. 500MPa grade high-strength weathering steel, with a base material tensile strength of more than 630MPa, a yield strength of more than 500MPa, and an elongation of not less than 18%, is an advanced high-strength steel for railway bridges. This high-strength weathering steel adopts the idea of ​​low carbon + alloying in composition design, and various alloy elements such as Ni, Cr, Cu, Mn, and Si are added to the base material; in terms of processing methods, controlled rolling and controlled cooling (TMCP) technology is adopted to strictly control its deformation and cooling process to achieve the purpose of controlling the organization and improving strength and toughness. However, the welding process is a reconstruction process of the base material organization and performance. Affected by the large amount of heat input during welding, a complex heat-affected zone is formed in the base material, which changes the original organization of the base material and reduces the performance of the original base material. The deposited metal between the parent materials is solidified by the molten welding material, has the structural characteristics of casting and contains a large number of inclusions, and has poor mechanical properties. Therefore, the higher the strength of the parent material, the more difficult it is to weld; the weld becomes a key factor limiting the strength and durability of the steel structure. Therefore, to promote the application of high-strength weathering steel in railway bridge construction, the welding problem must be solved first.

[0003] To solve the problem of high-strength steel welding, it is necessary to start from both welding materials and welding processes. First of all, as far as welding materials are concerned, there is an irreconcilable contradiction between improving weld strength and toughness. The reason is that the most direct and effective way to improve weld strength is to increase the amount of alloy elements added in welding materials and improve the strength of welds by optimizing the composition. However, the more alloy elements are added, the lower the toughness of the material will be while improving the strength; at the same time, the probability of weld defects will increase. Secondly, the welding methods currently used for welding high-strength weathering steel include submerged arc welding, gas shielded welding and manual arc welding. In the prior art, a composite welding process combining gas shielded welding and submerged arc welding is often used, and the operation process is complicated. For example, the Chinese invention patent application "Weathering Steel Welding Method" with publication number CN105014198A (publication date November 4, 2015) discloses a weathering steel welding method, and proposes a composite welding method of gas shielded welding primer + submerged arc welding filling for weathering steel with a strength grade of 345MPa; wherein the gas shielded welding uses flux-cored wire. Another example is the Chinese invention patent application with publication number CN117020369A, "A welding method for high-strength weather-resistant bridge steel in high-altitude areas" (publication date November 10, 2023). For Q550qENH high-strength weather-resistant bridge steel used in high-altitude areas, gas shielded welding + submerged arc welding is also used. This method has complicated operation procedures and requires preheating, base welding, root cleaning, submerged arc welding, insulation and slow cooling. The applicable steel plate thickness is 60mm, and the impact energy of the weld at -40℃ is not less than 60J.

[0004] Therefore, the prior art lacks welding materials and simple, easy and effective welding methods for 500MPa-grade high-strength weathering steel for railway bridges. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a welding material suitable for 500MPa-level high-strength weathering steel for railway bridges, and on this basis provides a welding method using the welding material. The present invention improves the welding performance of steel plates, enhances the strength, impact performance, and atmospheric corrosion resistance of welds and joints, achieves a reasonable match between the performance of welding joints and parent materials, ensures the safe service of high-strength weathering steel welded structures for railway bridges, and lays a foundation for the application and promotion of 500MPa-level high-strength weathering steel for railway bridges.

[0006] To this end, the present invention adopts the following technical solution:

[0007] A solid welding wire comprises the following chemical components in mass percentage based on the total mass of the solid welding wire: C 0.02%-0.08%, Mn 1.10%-1.60%, Si 0.18%-0.60%, P≤0.01%, S≤0.005%, Cr0.40%-0.60%, Ni 0.30%-0.60%, Cu 0.30%-0.45%, Mo0.05%-0.20%, V≤0.05%, and the balance is Fe and unavoidable impurities.

[0008] Preferably, based on the total mass of the solid welding wire, the solid welding wire contains the following chemical components in mass percentage: C 0.03% to 0.07%, Mn 1.10% to 1.50%, Si 0.18% to 0.50%, P≤0.01%, S≤0.005%, Cr 0.40% to 0.55%, Ni 0.30% to 0.55%, Cu 0.30% to 0.40%, Mo0.05% to 0.20%, V≤0.05%, and the balance is Fe and unavoidable impurities.

[0009] Preferably, based on the total mass of the solid welding wire, the mass sum percentage of the three elements Cr, Ni and Cu is 1.10% to 1.50%.

[0010] Preferably, the atmospheric corrosion resistance index I of the solid welding wire calculated according to the chemical composition is 6.0% to 7.0%; wherein the atmospheric corrosion resistance index I is calculated by formula (1): I = 26.01×(%Cu)+3.88×(%Ni)+1.20×(%Cr)+1.49×(%Si)+17.28×(%P)-7.29×(%Cu)×(%Ni)-9.10×(%Ni)×(%P)-33.39×(%Cu) 2 (1).

[0011] In the above formula (1), (% element) is the mass percentage of the element in the solid welding wire.

[0012] Preferably, the cross-sectional diameter of the solid welding wire is 1.2 mm.

[0013] The solid welding wire of the present invention is prepared by conventional methods in the art, and the main processes include: smelting, ingot casting, forging, rolling, wire rod pretreatment, wire drawing, copper plating, etc.

[0014] Another object of the present invention is to provide a welding method for 500MPa grade high strength weathering steel for railway bridges; the welding method is gas shielded welding, and the solid welding wire of the present invention is used in continuous root welding, filling welding and cap welding; the shielding gas is a mixed gas of 80% argon and 20% carbon dioxide; the welding process parameters include:

[0015] A. Setting of welding parameters

[0016] Welding voltage 26-30V, welding current 260-300A, welding speed 30-40cm / min, welding heat input 12-15kJ / cm, shielding gas flow 15-20L / min;

[0017] B. Setting of temperature parameters

[0018] (1) Base material preheating parameters

[0019] Steel plate thickness ≤ 32mm, no preheating; 32mm<steel plate thickness ≤ 60mm, preheating to no less than 80℃;

[0020] (2) Inter-pass temperature control

[0021] When the temperature of each weld is ≤150℃, proceed to the next weld.

[0022] Preferably, the welding process parameters also include:

[0023] C. Parent material groove form

[0024] The thickness of the steel plate is ≤16mm, with a V-shaped groove, an angle of 60°, and a 2mm blunt edge;

[0025] 16mm<steel plate thickness≤32mm, double V-shaped groove is adopted, angle is 60°, and 2mm blunt edge is left;

[0026] 32mm<steel plate thickness≤60mm, use U-shaped groove and leave 2mm blunt edge.

[0027] Preferably, the welding parameters are: welding voltage 27-29V, welding current 270-290A, welding speed 30-40cm / min, welding heat input 12-15kJ / cm, and shielding gas flow rate 15-20L / min.

[0028] Also preferably, the welding parameters can be adjusted as follows according to the thickness of the steel plate to be welded:

[0029] (1) The thickness of the steel plate is ≤16 mm, and the welding parameters of the base welding, filling welding and cap welding remain unchanged, including: 26 V ≤ welding voltage <28 V, 260 A ≤ welding current <280 A, welding speed 30-40 cm / min, welding heat input 12-15 kJ / cm, shielding gas flow 15-20 L / min;

[0030] (2) When the thickness of the steel plate is 16 mm or less and is less than 60 mm, the welding parameters for the base welding and the cover welding are set as follows: 26 V or less welding voltage and less than 28 V, 260 A or less welding current and less than 280 A, welding speed and 30 to 40 cm / min, welding heat input and 12 to 15 kJ / cm, and shielding gas flow rate and 15 to 20 L / min; the welding parameters for the filling welding are set as follows: 28 V or less welding voltage and 30 V, 280 A or less welding current and less than 300 A, welding speed and 30 to 40 cm / min, welding heat input and 12 to 15 kJ / cm, and shielding gas flow rate and 15 to 20 L / min.

[0031] Preferably, when the steel plate thickness is 32 mm < ≤ 60 mm, the parent material within 100 mm around the weld is preheated to 80-100° C.

[0032] Preferably, the weld temperature is measured using an infrared temperature measuring gun.

[0033] As a preferred embodiment, the present invention provides a welding method for 500MPa grade high-strength weathering steel for railway bridges with a thickness of ≤16mm, comprising the following specific process steps:

[0034] I. The butt joint adopts a single V-shaped groove with an angle of 60°, leaving a 2mm blunt edge, and removing the floating rust within 30mm of the weld to reveal the metallic luster;

[0035] II. Adjust welding process parameters

[0036] Welding voltage 26-30V, welding current 260-300A, welding speed 30-40cm / min, welding heat input 12-15kJ / cm, shielding gas flow 15-20L / min;

[0037] III. Using the solid welding wire of the present invention, weld the first pass under the parameters adjusted in step II, clean the surface oxide skin, measure the weld temperature with an infrared temperature gun, and perform the next weld until the weld temperature is ≤150°C;

[0038] IV. Repeat step III to continuously complete the base welding, filling welding and cap welding until the weld is 0 to 2 mm higher than the surface of the parent material and cool naturally.

[0039] As another preferred embodiment, the present invention provides a welding method for 500MPa grade high-strength weathering steel for railway bridges with a thickness of 16mm<≤60mm, comprising the following specific process steps:

[0040] (i) According to the thickness of the steel plate to be welded, the butt joint is grooved and the floating rust within 30mm of the weld is removed to reveal the metallic luster; wherein:

[0041] 16mm<steel plate thickness≤32mm, double V-shaped groove is adopted, angle is 60°, and 2mm blunt edge is left;

[0042] 32mm<steel plate thickness≤60mm, use U-shaped groove and leave 2mm blunt edge;

[0043] (ii) Preheating of base material

[0044] If the thickness of the steel plate is 16mm<32mm, no preheating is required; if the thickness of the steel plate is 32mm<60mm, preheat the steel plate within 100mm around the weld to no less than 80℃;

[0045] (iii) Root welding

[0046] (iii)-1. Adjust welding process parameters

[0047] 26V≤ welding voltage<28V, 260A≤ welding current<280A, welding speed 30~40cm / min, welding heat input 12~15kJ / cm, shielding gas flow 15~20L / min;

[0048] (iii)-2. Using the solid welding wire of the present invention, complete the first welding under the parameters adjusted in step (iii)-1, clean the surface oxide scale, measure the weld temperature with an infrared temperature measuring gun, and proceed to the next welding when the weld temperature is ≤150°C;

[0049] (iii)-3. Repeat step (iii)-2 until the base welding is completed;

[0050] (iv) Filling welding

[0051] (iv)-1 Adjust welding process parameters

[0052] 28V≤Welding voltage 30V, 280A≤Welding current <300A, welding speed 30~40cm / min, welding heat input 12~15kJ / cm, shielding gas flow 15~20L / min;

[0053] (iv)-2 When the temperature of the last weld completed in step (iii) is ≤150°C, complete the first pass of the filler weld under the welding parameters adjusted in step (iv)-1, clean the surface oxide scale, measure the weld temperature with an infrared temperature measuring gun, and proceed to the next weld when the weld temperature is ≤150°C;

[0054] (iv)-3 Repeat step (iv)-2 until the filling welding is completed;

[0055] (v) Cover welding

[0056] (v)-1 Adjust welding process parameters

[0057] 26V≤ welding voltage<28V, 260A≤ welding current<280A, welding speed 30~40cm / min, welding heat input 12~15kJ / cm, shielding gas flow 15~20L / min;

[0058] (v)-2 After the temperature of the last weld in step (iv) is ≤150℃, in step (v)

[0059] -1 After the first pass of the cap welding is completed under the adjusted parameters, proceed to the next pass;

[0060] (v)-3 Repeat step (v)-2 until the weld is 0 to 2 mm above the surface of the base material and cool naturally.

[0061] The number of weld passes for the base weld, the filler weld and the cap weld is conventional and can be easily determined by a person skilled in the art according to actual conditions.

[0062] The solid welding wire and welding method of the present invention are used to weld 500MPa-grade high-strength weathering steel for railway bridges, and the weld strength, impact and corrosion resistance can all achieve a good match with the parent material, breaking through the technical bottleneck of high-strength weathering steel welding. Specifically, the tensile strength of the deposited metal reaches more than 650MPa, and the yield strength is more than 600MPa; the tensile strength of the weld joint reaches more than 650MPa, and the yield strength is more than 530MPa. In terms of yield strength and tensile strength, it is even better than the parent material performance, achieving a good match with the parent material performance, and laying the foundation for the long-term and stable service of the welded joint. Under -40°C conditions, the weld impact absorption energy, KV2 reaches more than 140J, which is better than the parent material performance standard of 120J. At the same time, under -60°C conditions, the impact absorption energy, KV2 reaches more than 70J. The weld has excellent low-temperature impact resistance, which is of great significance for ensuring the safety of railway bridge steel structures under low-temperature environments.

[0063] In addition, the atmospheric corrosion resistance index I of the weld welded by the method of the present invention is 6.0%-7.0%, which is improved compared with the base material. Compared with the corrosion resistance of the base material, the corrosion resistance of the weld is appropriately enhanced, and it can be reasonably matched with the performance of the base material, achieving the best effect that the corrosion resistance of the weld is equivalent to that of the base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The present invention will be further described below in conjunction with the accompanying drawings.

[0065] Figure 1 Schematic diagram of the groove and weld of the steel plate to be welded in Example 4. The groove is V-shaped with an angle of 60°.

[0066] Figure 2 Schematic diagram of the groove and weld of the steel plate to be welded in Example 5. The groove is a double-sided U-shape. DETAILED DESCRIPTION

[0067] The present invention is described below with reference to specific examples. It will be appreciated by those skilled in the art that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention in any way.

[0068] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagents, etc. used in the following examples are commercially available products unless otherwise specified.

[0069] Embodiments 1 to 3 A solid welding wire

[0070] The chemical compositions of the solid welding wires of Examples 1 to 3 are shown in Table 1, and are prepared by the following method:

[0071] (1) Melting: Use electric furnace to melt molten steel according to the designed composition;

[0072] (2) Ingot casting: The molten steel is cast into ingots;

[0073] (3) Forging: Forging the cast steel ingot;

[0074] (4) Rolling: rolling the forged steel billet to form a steel wire rod with a cross-sectional diameter of 8 mm;

[0075] (5) Wire rod pretreatment: remove the oxide scale of the steel wire rod and clean it;

[0076] (6) Wire drawing: Wire drawing is performed on an automated production line to form a solid welding wire with a cross-sectional diameter of 1.2 mm;

[0077] (7) Copper plating: copper plating of welding wire in an automated production line;

[0078] (8) Packaging: The finished welding wire is wound and packaged in an automated production line.

[0079] Table 1 Chemical composition of solid welding wire of Examples 1 to 3

[0080] Example 1 Example 2 Example 3 C(％) 0.02 0.04 0.08 Mn(%) 1.10 1.30 1.60 Si(%) 0.18 0.45 0.60 P(％) 0.005 0.005 0.005 S(％) 0.003 0.003 0.003 Cr(％) 0.40 0.50 0.60 Ni(%) 0.30 0.40 0.60 Cu(%) 0.30 0.42 0.45 Mo(%) 0.05 0.15 0.20 V(％) 0.005 0.005 0.005 Fe(%) margin margin margin

[0081] Example 4

[0082] In this embodiment, the 500MPa high-strength weathering steel to be welded has a steel plate thickness of 16mm. The solid welding wire of Example 1 is used to perform gas shielded welding according to the following process and steps:

[0083] I. Press the steel plate butt joint Figure 1 As shown, a single-sided V-shaped groove is opened, with a groove angle of 60°, a blunt edge of 2mm, and a groove depth of 14mm. Remove the floating rust within 30mm of the weld to reveal the metallic luster.

[0084] II. Adjust welding parameters:

[0085] Welding voltage: 26V; welding current: 260A; shielding gas: 80% argon + 20% carbon dioxide, gas flow: 18L / min; controlled welding speed: 33cm / min.

[0086] III. Without preheating the base metal, the solid welding wire of Example 1 is directly used, and the welding process parameters of the welding machine adjusted in step II are used to complete the welding of the first weld; the surface oxide scale is cleaned, and the weld temperature is measured using an infrared temperature measuring gun. When the weld temperature is ≤150°C, the next welding is performed.

[0087] IV. Repeat step III until the weld is 0 to 2 mm above the surface of the base material and allow to cool naturally.

[0088] After the welded test plate was cooled, samples were taken for deposited metal and joint performance testing. The results are shown in Table 2.

[0089] Example 5

[0090] In this embodiment, the 500MPa high-strength weathering steel to be welded has a steel plate thickness of 60mm. The solid welding wire of Example 2 is used to perform gas shielded welding according to the following process and steps:

[0091] I. Press the steel plate butt joint Figure 2 As shown, double-sided U-shaped grooves are opened, with a blunt edge of 2mm and a groove depth of 14mm. Floating rust within 30mm of the weld is removed to reveal the metallic luster.

[0092] II. Preheat the base steel plate within 100mm around the weld to 80℃.

[0093] III. Adjust welding parameters for base welding:

[0094] The welding voltage is 26V; the welding current is 260A; the shielding gas is 80% argon gas + 20% carbon dioxide, and the gas flow rate is 18L / min; the welding speed is controlled to be 33cm / min. The solid welding wire of Example 2 is used to complete the welding of 5 welds of the base welding according to the adjusted welding parameters; after each welding, the surface oxide scale is cleaned, and the weld temperature is measured with an infrared temperature measuring gun. When the weld temperature is ≤150°C, the next welding is carried out.

[0095] IV. Adjust welding parameters for filling welding:

[0096] Welding voltage 28V; welding current 280A; shielding gas argon 80% + carbon dioxide 20%, gas flow 18L / min; control welding speed 33cm / min. Complete the filling welding according to the adjusted welding parameters; after each welding, clean the surface oxide skin, use an infrared temperature gun to measure the weld temperature, and wait until the weld temperature is ≤150℃ before welding the next one, until the weld is 5mm away from the surface.

[0097] V. Adjust welding parameters for cover welding

[0098] Welding voltage 26V; welding current 260A; shielding gas argon 80% + carbon dioxide 20%, gas flow 18L / min; control welding speed 33cm / min. Complete the cap welding according to the adjusted welding parameters; after each welding, clean the surface oxide scale, use an infrared temperature gun to measure the weld temperature, and wait until the weld temperature is ≤150℃ before welding the next one; until the weld is 0-2mm higher than the surface of the parent material, cool naturally.

[0099] After the welded test plate was cooled, samples were taken for deposited metal and joint performance testing. The results are shown in Table 2.

[0100] Comparative Example 1

[0101] Commercially available solid welding wire was used to weld steel plates of the same strength as in Example 4, and the other process steps were the same as in Example 4.

[0102] After the welded test plate was cooled, samples were taken for deposited metal and joint performance testing. The results are shown in Table 2.

[0103] Comparative Example 2

[0104] The steel plates to be welded in this comparative example are the same as those in Example 4, and the solid welding wire of Example 1 is also used. The welding process steps are basically the same as those in Example 4, except that in Step III and Step IV, after each weld is completed, the surface oxide scale is cleaned, and the next weld is carried out without waiting for the weld temperature to drop below 150°C.

[0105] After the welded test plate was cooled, samples were taken for deposited metal and joint performance testing. The results are shown in Table 2.

[0106] Table 2 Test results of deposited metal and joint performance after welding obtained in various embodiments and comparative examples

[0107]

[0108] a : Not determined.

[0109] The measurement results in Table 2 show that the properties of the weld obtained by using the solid welding wire of the present invention in combination with the welding method of the present invention are better than those of the comparative example, and the performance match with the parent material is better.

Claims

1. A solid welding wire, comprising the following chemical components in mass percentage based on the total mass of the solid welding wire: C 0.02% to 0.08%, Mn 1.10% to 1.60%, Si 0.18% to 0.60%, P≤0.01%, S≤0.005%, Cr0.40% to 0.60%, Ni 0.30% to 0.60%, Cu 0.30% to 0.45%, Mo 0.05% to 0.20%, V≤0.05%, and the balance is Fe and unavoidable impurities.

2. The solid welding wire according to claim 1, characterized in that: Based on the total mass of the solid welding wire, the solid welding wire contains the following chemical components in mass percentage: C 0.03%~0.07%, Mn 1.10%~1.50%, Si0.18%~0.50%, P≤0.01%, S≤0.005%, Cr0.40%~0.55%, Ni 0.30%~0.55%, Cu0.30%~0.40%, Mo 0.05%~0.20%, V≤0.05%, and the balance is Fe and unavoidable impurities.

3. The solid welding wire according to claim 1 or 2, characterized in that: Based on the total mass of the solid welding wire, the mass sum percentage of the three elements Cr, Ni and Cu is 1.10% to 1.50%; Preferably, the atmospheric corrosion resistance index I of the solid welding wire calculated according to the chemical composition is 6.0% to 7.0%; wherein the atmospheric corrosion resistance index I is calculated by formula (1): I=26.01×(%Cu)+3.88×(%Ni)+1.20×(%Cr)+1.49×(%Si)+17.28×(%P)-7.29×(%Cu)×(%Ni)-9.10×(%Ni)×(%P)-33.39×(%Cu) 2 (1)。 4. The solid welding wire according to any one of claims 1 to 3, characterized in that: The cross-sectional diameter of the solid welding wire is 1.2 mm.

5. A welding method for 500MPa grade high strength weathering steel for railway bridges; the welding method is gas shielded welding, and the solid welding wire described in any one of claims 1 to 4 is used in continuous root welding, filling welding and cap welding; the shielding gas is a mixed gas of 80% argon and 20% carbon dioxide; the welding process parameters include: A. Setting of welding parameters Welding voltage 26-30V, welding current 260-300A, welding speed 30-40cm / min, welding heat input 12-15kJ / cm, shielding gas flow 15-20L / min; B. Setting of temperature parameters (1) Base material preheating parameters Steel plate thickness ≤ 32mm, no preheating; 32mm<steel plate thickness ≤ 60mm, preheating to no less than 80℃; (2) Inter-pass temperature control When the temperature of each weld is ≤150℃, proceed to the next weld.

6. The welding method according to claim 5, characterized in that: The welding process parameters also include: C. Parent material groove form The thickness of the steel plate is ≤16mm, with a V-shaped groove, an angle of 60°, and a 2mm blunt edge; 16mm<steel plate thickness≤32mm, double V-shaped groove is adopted, angle is 60°, and 2mm blunt edge is left; 32mm<steel plate thickness≤60mm, use U-shaped groove and leave 2mm blunt edge.

7. The welding method according to claim 5, characterized in that: The welding parameters are as follows: welding voltage 27-29V, welding current 270-290A, welding speed 30-40cm / min, welding heat input 12-15kJ / cm, and shielding gas flow rate 15-20L / min; Preferably, the welding parameters are adjusted as follows according to the thickness of the steel plate to be welded: (1) The thickness of the steel plate is ≤16 mm, and the welding parameters of the base welding, filling welding and cap welding remain unchanged, including: 26 V ≤ welding voltage <28 V, 260 A ≤ welding current <280 A, welding speed 30-40 cm / min, welding heat input 12-15 kJ / cm, shielding gas flow 15-20 L / min; (2) When the thickness of the steel plate is 16 mm or less and is less than 60 mm, the welding parameters for the base welding and the cover welding are set as follows: 26 V or less welding voltage and less than 28 V, 260 A or less welding current and less than 280 A, welding speed and 30 to 40 cm / min, welding heat input and 12 to 15 kJ / cm, and shielding gas flow rate and 15 to 20 L / min; the welding parameters for the filling welding are set as follows: 28 V or less welding voltage and 30 V, 280 A or less welding current and less than 300 A, welding speed and 30 to 40 cm / min, welding heat input and 12 to 15 kJ / cm, and shielding gas flow rate and 15 to 20 L / min.

8. The welding method according to claim 5, characterized in that: When the thickness of the steel plate is 32mm<≤60mm, the parent material within 100mm around the weld should be preheated to 80~100℃; Preferably, the weld temperature is measured using an infrared temperature measuring gun.

9. A welding method for 500MPa grade high-strength weathering steel for railway bridges with a thickness of ≤16mm, comprising the following specific process steps: I. The butt joint adopts a single V-shaped groove with an angle of 60°, leaving a 2mm blunt edge, and removing the floating rust within 30mm of the weld to reveal the metallic luster; II. Adjust welding parameters Welding voltage 26-30V, welding current 260-300A, welding speed 30-40cm / min, welding heat input 12-15kJ / cm, shielding gas flow 15-20L / min; III. Using the solid welding wire according to any one of claims 1 to 4, welding the first pass under the parameters adjusted in step II, cleaning the surface oxide scale, measuring the weld temperature with an infrared temperature gun, and performing the next welding when the weld temperature is ≤150°C; IV. Repeat step III to continuously complete the base welding, filling welding and cap welding until the weld is 0 to 2 mm higher than the surface of the parent material and cool naturally.

10. A welding method for 500MPa grade high strength weathering steel for railway bridges with a thickness of 16mm < ≤ 60mm, comprising the following specific process steps: (i) According to the thickness of the steel plate to be welded, the butt joint is grooved and the floating rust within 30mm of the weld is removed to reveal the metallic luster; wherein: 16mm<steel plate thickness≤32mm, double V-shaped groove is adopted, angle is 60°, and 2mm blunt edge is left; 32mm<steel plate thickness≤60mm, use U-shaped groove and leave 2mm blunt edge; (ii) Preheating of base material If the thickness of the steel plate is 16mm<32mm, no preheating is required; if the thickness of the steel plate is 32mm<60mm, preheat the steel plate within 100mm around the weld to no less than 80℃; (iii) Root welding (iii)-1. Adjust welding process parameters 26V≤ welding voltage<28V, 260A≤ welding current<280A, welding speed 30~40cm / min, welding heat input 12~15kJ / cm, shielding gas flow 15~20L / min; (iii)-2. Using the solid welding wire of the present invention, complete the first welding under the parameters adjusted in step (iii)-1, clean the surface oxide scale, measure the weld temperature with an infrared temperature measuring gun, and proceed to the next welding when the weld temperature is ≤150°C; (iii)-3. Repeat step (iii)-2 until the base welding is completed; (iv) Filling welding (iv)-1 Adjust welding process parameters 28V≤Welding voltage 30V, 280A≤Welding current <300A, welding speed 30~40cm / min, welding heat input 12~15kJ / cm, shielding gas flow 15~20L / min; (iv)-2 When the temperature of the last weld completed in step (iii) is ≤150°C, complete the first pass of the filler weld under the welding parameters adjusted in step (iv)-1, clean the surface oxide scale, measure the weld temperature with an infrared temperature measuring gun, and proceed to the next weld when the weld temperature is ≤150°C; (iv)-3 Repeat step (iv)-2 until the filling welding is completed; (v) Cover welding (v)-1 Adjust welding process parameters 26V≤ welding voltage<28V, 260A≤ welding current<280A, welding speed 30~40cm / min, welding heat input 12~15kJ / cm, shielding gas flow 15~20L / min; (v)-2 When the temperature of the last weld completed in step (iv) is ≤150°C, complete the first pass of the cap weld under the parameters adjusted in step (v)-1 and proceed to the next pass; (v)-3 Repeat step (v)-2 until the weld is 0 to 2 mm above the surface of the base material and cool naturally.

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